The present application relates to the field of external beam radiotherapy. It finds particular application with particle therapy. It also relates to medical and other applications where an object is examined, or scanned, to determine a treatment plan and then treated according to the treatment plan using an external beam.
Cancer is one of the leading causes of death in humans. Advancements in medical technologies have played an intricate role in both identifying tumors in the early stages and treating the tumors by either slowing their growth or shrinking tumors to a size that can safely be removed or possibly extinguished. These advancements have also identified techniques and/or systems that are less invasive and less uncomfortable to a patient undergoing treatment than techniques and/or systems used in years past.
External beam radiotherapy, and in particular particle therapy, is a relatively recent development for the treatment of tumors. While it was suggested in the 1940s that particle technology could be capable of treating cancer, it was not implemented in a medical (e.g., hospital) setting until the 1990s. Since then, over sixty thousand patients, with over fifty different types of tumors, have been treated using particle therapy at the approximately thirty particle therapy treatment facilities all over the world.
External beam radiotherapy uses beams of protons, neutrons, ions, etc. to penetrate tissue and treat portions of a patient that have been identified as tumors. The beams are targeted at the tumor and are configured to damage the DNA of tissue cells of the tumor. Because tumors are generally not able to repair damaged DNA and/or repair damaged DNA more slowly than non-tumor cells, the beams may ultimately cause the cells to die (e.g., causing the tumor to shrink, possibly to the point of extinction).
Because the beams are configured to damage the DNA of tissue cells, it is important to mitigate the number of healthy cells that the beam contacts (e.g., particularly near the Bragg peak where the dose delivered to the tissue by the beam is at its maximum). Thus, generally before beams are emitted towards the tumor, a treatment plan is developed to identify a specific target region and/or to determine the characteristics of the particles that should be emitted toward the tumor, for example.
To generate a treatment plan, a patient is placed within a radiation scanner, such as a computed tomography (CT) scanner, and the patient is examined. During the examination, radiation is emitted from a radiation source towards the patient or, more particularly, towards a region of the patient in which the tumor is positioned (e.g., based upon diagnostic imaging). Radiation that traverses the patient is detected by a detector array positioned on a substantially diametrically opposite side of the patient relative to the radiation source. Using signals or data generated by the detector array (or, more generally, the radiation scanner) and indicative of the detected radiation, a treatment plan may be developed. Such a treatment plan may specify the precise orientation of the tumor in the patient, the desired trajectory of the beams (or rather, the orientation of an irradiation component emitting the beam relative to the patient), the types of particle to be used, and/or the energy at which particles should be accelerated (e.g., to yield a Bragg peak that falls within the tissue cells of the tumor), for example.
After the examination, the patient is moved from an examination room with the radiation scanner to a treatment room, where the particle radiation (also referred to as particle beams) may be delivered to the patient. Stated differently, the patient is positioned on a first support article (e.g., a first bed) for an examination, stands up and walks from an examination room to a treatment room, and is positioned on a second support article (e.g., a second bed) for treatment. Once positioned on the second support article, the patient may be treated as specified by the treatment plan (e.g., which was developed based upon an examination while the patient was positioned on the first support article).
Generally, the irradiation component is configured to emit particle beams in such a way as to cause the beams to impinge the tumor from a plurality of angles, or to impinge a plurality of locations on the tumor. For example, the irradiation component may be coupled to a rotating gantry that rotates about the patient (and the tumor) allowing the irradiation component to emit beams from a plurality of angles relative to the tumor. Stated differently, during treatment, the irradiation component may begin the treatment by emitting beams at a first orientation relative to the patient; the irradiation component may then be shut off (or a shutter may be positioned to block the beams from escaping the irradiation component), and the irradiation component may be rotated (by the rotating gantry) to a second orientation (different than the first orientation) relative to the patient. The irradiation component may then be turned back on (or the shutter removed), and a second set of beams may be emitted from the irradiation component. Such a technique may be referred to as “painting” the tumor (e.g., the beams impinge the tumor from a plurality of angles until a specified portion of tissue cells of the tumor have been struck by a beam).
While external beam radiotherapy and, more particularly, particle therapy have proven useful for treating numerous types of tumors, the adoption of particle therapy has been limited (to approximately thirty facilities) because of the cost of a particle therapy system, which may be on the order of hundreds of millions of dollars, and/or because of difficulties with getting the beam to hit the precise location specified in the treatment plan due to shifting of internal organs of the patient between the first support article (from which the treatment plan is developed) and the second support article (whereon treatment occurs).